Piston for internal-combustion engines



0. ALT.

PISTON FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED NOV. 25, 1921.

1 ,405,8 87 Patented Feb. 7, 1922.

jvemian UNITED STATES PATENT OFFICE.

OTTO ALT, OF KIEL, GERMANY, ASSIGNOR TO FRIED. KRUI'PAITIENGESELLSOHAFT, GERMANIAWERFT, OF KIEL-GAARDEN, GERMANY.

PISTON FOR INTERNAL-COMBUSTION ENGINES.

Application filed November 25, 1921.

To all whom it may concern:

Be it known that I, Or'ro ALT, residing at Kiel, Germany, a citizen ofthe German Republic, have invented a certain new and useful Improvementin Pistons for Internal-Combustion Engines, (for which I have filedapplication for patent in German Nov. 22, 1920, under Serial No. K25,304, 46 C.) of which the following is a specification.

This invention relates to istons for internal combustion engines of thekind in which there is inserted in the piston bottom a mushroom-shapedprotecting body intended to protect the bottom surface facing thecombustion chamber of the cylinder, against the destructive action ofthe thin flames arising at the nozzles of the fuel-injecting valves.

The object of the present invention is to produce a piston of the kinddescribed which, even if made with large dimensions, has a highdurability and works satisfactorily even without being cooled by waterand which can be repaired in an easy and convenient way if damaged.

According to the invention, this object is chiefly attained by the factthat the surface, facing the combustion chamber, of the mushroom-shapedprotecting body, is entirely or partially covered by aspecial discshapedprotecting plate consisting of a material which offers a particularlygreat resistance against high temperatures, said protecting plate beingconnected to the protecting body merely on its centre or in the vicinitythereof, and the outer edge of which has lateral clearance so that theplate can freely expand in all directions and, after removing thecylinder cover, may be easily replaced from the piston bottom side.

An embodiment of the subject-matter of the invention is shown by wayof'example in the accompanying drawing which shows, in section, a pistonof a single-acting internal combustion engine with oscillating pistonrod.

The piston body A is constructed so as to form, at its end facing thecombustion chamber of the cylinder, an annular hollow body a theinterior a, of which is intended to receive in the known manner, acooling liquid. In a central recess of the hollow body a there isinserted a mushroom-shaped protecting body B which covers the greaterportion of the front surface of the body a Specification of LettersPatent.

Patented Feb. 7,1922.

Serial No. 517,758.

and the extension 6' of which is connected, in the manner illustrated,to the piston body A by screw bolts. Between the outer edge 6 of theprotecting body B and the piston body as well as between the latter andthe extension 6 there is provided lateral clearance so that the body Bis capable of expanding freely relatively to the piston body A, evenwith very high temperatures.

In order to prevent erosions at the points where the thin flames ejectedat the fuel nozzles strike the projecting body B which is usually madeof the same or similar material as the piston A, the body B is coveredby a special disc-shaped protecting plate C which consists of a materialoffering a particularly strong resistance against being destroyed byhigh temperatures. This protecting plate has on its lower side atap-shaped screwthreaded projection c by means of which it is screwedinto the protecting body B from above. As the rotecting body B and theprotecting plate 8 are thus rigidly con,- nected to each other in theircentres only and, moreover, -a lateral clearance exists between the edgeof the plate C and the body B, the plate C is capable of expandingfreely in all directions. Any unintentional unscrewingofthe plate C outof the body B during the working of the engine is pre vented by a safetyscrew D.

In place of the tap-shaped screw-threaded projection 0, which is made inone piece with the protecting plate C, a separate screw bolt mayobviously be provided havin .a sunk-in head covered by materialresistlng to high temperatures. Further, instead of a single screw bolta plurality of bolts may be'used which must, however, be located in theimmediate vicinity of the centre of the projecting plate in order toallow the latter to freely expand.

Preferably the radius of curvature 1" of the upper cavity of theprotecting plate C is smaller than the radius of curvature R of thecavity of the body B surrounding the plate C. This arrangement offersthe advantage that the thin flames striking the protecting plateC flowaway in lateral direction without directly contacting the protectingbody B, as indicated by the arrows in the drawlngs, so that thedurability of the body B is extraordinarily increased.

Whereas the protecting plate constructed in accordance with theinvention is able to of a heat-protecting body freely expand in alldirections so that no warping of the plate and destroying of the same,resulting therefrom, can take place, and whereas the describedconstruction makes it possible to easil replace the protecting plate ifdamage owing to unforseen circumstances, the invention forms a means forproducing larger pistons than hitherto could be made, without awatercooling arrangement. It is to be noted, however, that the inventioncan be employed both in water-cooled pistons and in pistons not cooledby water.

Claims.

1. In a piston for internal combustion engines the combination with thepiston body, connected to said piston body at the combustion chamberside, and a second protecting body consisting of highly heat-resistingmaterial and covering the portion of said first-named protecting bodywhich is most exposed to heat.

2. In a piston for internal combustion engines the combination with thepiston body, of a heat-protecting body connected to said piston-body atthe combustion chamber side, and a disc-shaped second protecting bodyconsisting of highly heat-resisting material and covering the portion ofsaid first-named protecting body which is most exposed to heat,clearance being provided between said first-named protecting body andsaid second protecting body to enable free expansion of the latter.

3. In a piston for internal combustion engines the combination with thepiston body, of a heat-protecting body connected to said piston body atthe combustion chamber side, and a disc-shaped second protecting bodyconsisting of highly heat-resisting material and covering the portion ofsaid first-named protecting body which is most exposed to heat, andconnected to the first-named protecting body near to its centre,clearance being provided between said first-named protecting body andsaid second protecting body to enable free expansion of the latter.

4. In a piston for internal combustion engines the combination with thepiston body, of a heat-protecting body connected to said piston body atthe combustion chamber side and having a concave protecting surface, adisc-shaped second protecting body consisting of highly heat-resistingmaterial and covering the portion of said first-named protecting bodywhich is most exposed to heat, and having likewise a concave protectingsurface the radius of curvature of which is smaller than that of theprotecting surface of the first-named protecting body.

5. In a piston for internal combustion engines the combination with apiston body, of a heat-protecting body connected to said piston body atthe combustion chamber side, and having a concave protecting surface, adisc-shaped second protecting body consisting of highly heat-resistingmaterial and coverin the portion of said first-named protecting odywhich is most exposed to heat, and having a' concave protecting surface,the radius of curvature of which is smaller than that of the protectingsurface of said first-named protecting body, these two protecting bodiesbeing connected to each other in the vicinity of their centres,clearance bein provided between said two bodies to enab e free expansionof said second bod The foregoing specification signed at iel,

Germany, this 19th day of October, 1921.

I o'r'ro ALT.

